Abstract
Since 1964, a continuous grazing or whole year grazing system of the Japanese Black Breed of Cattle has been tried at the Ontake Stock-Farm of Otaki village in Nagano Prefecture. There, the woodlands in the 2nd Pasture of the Farm, have been used exclusively for winter grazing immediately after summer grazing in the grasslands of the 1st Pasture. The woodland pasture is situated at about 1, 600m above sea level on the south-facing slope of Mt. Ontake, being constructed mainly of such trees as birch (Betula platyphylla var. japonica), oak (Quercus rnongolica var. grosseserrata), larch (Larix leptolepis), and partly accompanied with sub-alpine trees such as hemlock (Tsuga diversifolia). The woodland floor is completely covered by a dwarf bamboo (Sasa senanensis) which offers indispensable fodders for grazing cattle throughout the winter season. On August 1968, some ecological surveys were conducted in the woodland pasture of this Farm to throw light on the influence of winter grazing on this dwarf bamboo. The plots surveyed were selected in the areas of heavy grazing and early spring grazing in addition to the ordinary winter grazing area. Under repeated winter grazing, plant height, density, branching, number and shape of leaves, leaf weight, and standing crop of the dwarf bamboo were affected in the following ways through the complicated process : Height : decreased lineally in parallel with the grazing intensity, besides much expanding variability in height. Density : decreased, but not so linear as the plant height. Branching : increased in number in parallel with the grazing intensity, and dead branches also increased. Number of leaves : increased dynamically as intensification of grazing. Shape of leaves : leaf area decreased, becoming slender in shape. Leaf weight : weight ratio of leaves to all organs above the ground decreased under ordinary grazing, though increased under heavy grazing. Standing crop : decreased in parallel with the grazing intensity. The data described above were compared with those of the summer grazing at the Takiue Station which had already been reported in the part 1 of this thesis. The information thus obtained supports the suggestions that the tendencies of which the dwarf bamboo affected by winter grazing represent are essentially the same as those by summer grazing. However, the degree of damages from which the dwarf bamboo suffers is considerably slight under winter grazing than under summer grazing.
